Stoic Ethics: Definition of the End by William O. Stephens

"Stoicism is known as a eudaimonistic theory, which means that the culmination of human endeavor or ‘end’ (telos) is eudaimonia, meaning very roughly “happiness” or “flourishing.” The Stoics defined this end as “living in agreement with nature.” “Nature” is a complex and multivalent concept for the Stoics, and so their definition of the goal or final end of human striving is very rich.

"The first sense of the definition is living in accordance with nature as a whole, i.e. the entire cosmos. Cosmic nature (the universe), the Stoics firmly believed, is a rationally organized and well-ordered system, and indeed coextensive with the will of Zeus, the impersonal god. Consequently, all events that occur within the universe fit within a coherent, well-structured scheme that is providential. Since there is no room for chance within this rationally ordered system, the Stoics’ metaphysical determinism further dictated that this cosmic Nature is identical to fate. Thus at this level, “living in agreement with nature” means conforming one’s will with the sequence of events that are fated to occur in the rationally constituted universe, as providentially willed by Zeus."